In 1968 a disposable blood processing bowl was introduced by the inventor, Allen Latham, Jr., in a paper entitled "A New Approach to Automated Centrifugal Processing of Blood" at the 21st Annual Meeting of the American Association of Blood Banks. Mr. Latham described a system for processing blood using an expendable, or disposable, centrifuge rotor in the form of a relatively inexpensive bowl. The system was proposed for use in a number of pheresis procedures, such as plasmapheresis and plateletpheresis. In these processes, whole blood is taken from a donor and various blood components are separated from the whole blood and harvested while some components are returned to the donor. The system was also suggested for use in cell washing, such as in deglycerization, in which thawed deglycerized red cells are washed to remove the glycerine preservative before being infused in a patient.
In operation, the bowl is held in a chuck which is attached to a spindle and driven by a motor. The bowl consists of a rotor, or bowl body portion in which blood component is separated and a stator portion consisting of an input and output port. A rotary seal couples the stator to the rotor. One side of the input port is connected through a first peristaltic pump to a source of whole blood from a donor and the other side is in fluid communication with a fractionation volume in the rotor. Anticoagulant is mixed with the whole blood prior to entry into the centrifuge bowl.
The rotor is rotated at a fixed speed and various blood fractions are collected at the output port and directed into appropriate containers, such as plastic bags, by diverting the flow through plastic tubing in accordance with the setting of three-way clamp/switches.
Fractionation within the centrifuge is determined by the relative densities of the different cell components being separated and collected. The various cell fractions pass through the outlet port of the centrifuge bowl by progressive displacement from the lower portion of the bowl.
The bowl consists of two major components. One is a rotatable bowl body with an inner core mounted coaxial to a central longitudinal axis through the bowl body. The other is a rotary seal and header assembly, which is provided on top of the bowl body.
The bowl body is divided into two chambers, the first is an upper collection chamber adjacent an upper radially extending collection passageway leading to the output port. The second is a separation chamber formed between the longitudinally extending cylindrical wall of the core and the side wall of the bowl body.
Anticoagulated whole blood introduced to the bowl body via the fixed input port is coupled to the bottom of the bowl body by a fixed inlet tube coupled to the input port and extending longitudinally therefrom along a central longitudinal axis to the bottom wall of the bowl body.
Whole blood is coupled to the separation chamber via one or more radially extending introduction passageways formed between an inner surface of the lower bowl body wall and a lower radially extending wall of the core which extends in parallel to the lower bowl body wall leaving a narrow entrance at the extended outer diameter of the bowl for introduction of whole blood from the introduction chamber into the separation chamber.
Separated less dense whole blood component in the separation chamber is coupled to the collection chamber via a passageway formed between radially inwardly extending wall portions of the core and bowl body leading to the upper collector passageway and through the output port. The upper collector passageway is formed by a pair of opposed radially outwardly extending members which lead to a longitudinally extending coaxial passageway coupled to the outlet port.
The header assembly must remain fixed, since the inlet and outlet tubing to, or from, a donor or patient, is coupled to it. The rotary seal provides an appropriate interface between the fixed header and the rotating bowl body.
The system, including the bowl, interconnecting tubing and receptacles, are connected together and sterilized in advance of use, so that they arrive in sterile form ready for immediate use. All parts, other than the rotary seal assembly, are generally made from blood-compatible plastic, such as polycarbonate (for the bowl), or polyethylene (for the tubing and receptacles).
One of the disadvantages of the centrifuge bowls described above is that, when the last of the less dense components, i.e. plasma, platelets, etc., are being displaced by passage through the outlet port, the supply of an anticoagulated whole blood must be interrupted to prevent the outflow of the more dense components, i.e., red blood cells (RBC). The centrifuge is stopped leaving concentrated RBC in the bowl which are then collected by suctioning out through the inlet port prior to commencing another separation cycle.
As noted by Panzani in U.S. Pat. No. 4,859,333 this interruption is particularly disadvantageous in the case of intraoperative autotransfusion where whole blood is washed and RBC separated for rapid reinfusion. Panzani's solution to this problem is to add a third port 12(a) connected to an additional central conduit 12 which extends to the bottom of the bowl and which is sealed from the conventional inlet tubing by a gasket 13. (U.S. Pat. No. 4,859,333 Col. 4, lines 9-20).
A vacuum or negative pressure is applied to the third port where it is desired to collect RBC which are drawn up the additional conduit 12 which is in communication with bottom passage 16, which is in the peripheral communication with outer passage 7 where the concentrated RBC are located (U.S. Pat. No. 4,859,333, Col. 4, lines 42-54).